Sealed compressor and refrigerator including sealed compressor

ABSTRACT

A sealed compressor ( 100 ) of the present invention comprises an electric component ( 111 ), a compression component ( 117 ), and a sealed container ( 101 ), the compression component includes a shaft ( 119 ), a cylinder block ( 129 ), a piston ( 133 ), and a crank weight ( 126 ), a rotor ( 115 ) of the electric component has a cylindrical shape, contains a cylindrical space therein, and includes an upper section ( 116 ) in which a lower portion of a bearing ( 131 ) of a cylinder block is fitted into the cylindrical space, a lower section ( 115   e ) to which a lower portion of the main shaft inserted into the through-hole of the bearing and inserted into the cylindrical space is fixedly fitted, and a balance weight ( 170, 270 ) placed on an opposite side of the crank weight with respect to the piston.

TECHNICAL FIELD

The present invention relates to a sealed compressor and a refrigerator including the sealed compressor. Particularly, the present invention relates to a sealed compressor used in a heat pump cycle such as a refrigeration cycle, and a refrigerator including the sealed compressor.

BACKGROUND ART

Conventionally, there is known a sealed compressor which is thinned and intended to mitigate the vibration caused by a piston, which is one of sealed compressors in which a working fluid is compressed by the piston into high-temperature and high-pressure states and the resulting working fluid is discharged to a heat pump cycle. For example, in the sealed compressor disclosed in Patent Literature 1, the upper surface of a rotor is provided with a recess, and the lower portion of a support frame is fitted into the recess. This allows the support frame and the recess to overlap with each other, and their lengths to be reduced. In this way, the sealed compressor is thinned.

A crankshaft is composed of a body shaft, an eccentric plate section formed at the upper end of the body shaft, and an eccentric shaft provided at the eccentric plate section. The body shaft of the crankshaft is rotatably inserted into a hole of the support frame. The lower portion of the body shaft protrudes downward from the hole of the support frame and is fixedly fitted to a rotor. The eccentric shaft of the crankshaft protrudes upward from the support frame, and a balance weight is mounted to the upper end portion of the eccentric shaft. The piston is coupled to the eccentric shaft and inserted into a cylinder bore of the support frame. In such a sealed compressor, when the rotor rotates, the eccentric shaft of the crankshaft eccentrically rotates, and the piston reciprocates within the cylinder bore. At this time, the inertia force due to the reciprocation motion of the piston and the eccentric rotation motion of the eccentric shaft cause an unbalanced component of a centrifugal force, which is a cause of the vibration of the sealed compressor. To avoid this, the vibration of the sealed compressor is mitigated by cancelling the unbalanced component by the centrifugal force of a crank weight mounted to the eccentric shaft.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Laid-Open Patent Application Publication No. 2002-70740

SUMMARY OF INVENTION Technical Problem

However, in the above described conventional sealed compressor, in a case where the amount of the working fluid to be discharged is increased, the volume of the cylinder bore and the outer diameter of the piston are increased, or the stroke amplitude of the piston is increased. In such a case, the unbalanced component increases. Therefore, it is necessary to increase the weight of the crank weight for cancelling the unbalanced component to increase the centrifugal force.

However, if the centrifugal force of the crank weight is increased so that the centrifugal force and the unbalanced component are balanced, a rotational moment generated by the fact that the piston and the crank weight are distant from each other would increase. This increases the vibration of the runout of the crankshaft in an inclined state, and as a result, increases a vibration and a noise in the sealed compressor.

Especially, in the above stated sealed compressor, a cantilever bearing configuration is employed, in which only one end of the crankshaft is supported by the support frame. Since the lower portion of the support frame is fitted into the recess, the rotor and the crankshaft are fixedly fitted to each other in a small range, which reduces a stiffness of the fitted portions. In this case, the vibration of the runout of the crankshaft is transmitted to the rotor, and thereby the vibration of the rotor tends to be amplified. This significantly increases the vibration and the noise in the sealed compressor, which is due to the vibration of the crankshaft.

The present invention is directed to solving the above described problem, and an object of the present invention is to provide a thinned sealed compressor which can reduce a vibration and a noise, and a refrigerator including the sealed compressor.

Solution to Problem

According to an aspect of of the present invention, there is provided a sealed compressor comprising: an electric component including a stator and a rotor which is rotatable with respect to the stator; a compression component activated by the electric component placed below the compression component; and a sealed container accommodating the electric component and the compression component; wherein the compression component includes: a shaft including a main shaft, and an eccentric shaft which is eccentric with respect to the main shaft; a cylinder block including a bearing having inside thereof a through-hole extending vertically and supporting the main shaft inserted into the through-hole such that the main shaft is rotatable, and a cylinder having a compression chamber inside thereof; a piston which is coupled to the eccentric shaft and is reciprocatable within the compression chamber; and a crank weight mounted to an upper portion of the eccentric shaft; wherein the rotor has a cylindrical shape and contains a cylindrical space therein; and wherein the rotor includes: an upper section in which a lower portion of the bearing is fitted into the cylindrical space; a lower section which is smaller in inner diameter than the upper section, a lower portion of the main shaft inserted into the through-hole of the bearing and inserted into the cylindrical space being fixedly fitted to the lower section; and a balance weight placed on an opposite side of the crank weight with respect to the piston.

Advantageous Effects of Invention

The present invention has the above described configuration, and has advantages that it is possible to provide a sealed compressor which can reduce a vibration and the noise, and a refrigerator including the sealed compressor.

The above and further objects, features and advantages of the invention will more fully be apparent from the following detailed description of a preferred embodiment, with reference to accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a sealed compressor according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged view showing a region A of FIG. 1.

FIG. 3A is a cross-sectional view of a rotor for use in the sealed compressor of FIG. 1, which is taken along a plane perpendicular to the axis of the rotor.

FIG. 3B is a cross-sectional view of the rotor which is taken along broken lines B-B of FIG. 3A.

FIG. 4 is a view showing an external appearance of the rotor of FIG. 3A, when viewed from a lower side.

FIG. 5 is a view schematically showing forces applied to a shaft of the sealed compressor of FIG. 1.

FIG. 6 is a cross-sectional view showing a sealed compressor according to Embodiment 2 of the present invention.

FIG. 7 is a view schematically showing forces applied to a shaft of the sealed compressor of FIG. 6.

FIG. 8 is a cross-sectional view schematically showing a refrigerator according to Embodiment 3 of the present invention.

DESCRIPTION OF EMBODIMENTS

According to a first aspect of the present invention, there is provided there is provided a sealed compressor comprising: an electric component including a stator and a rotor which is rotatable with respect to the stator; a compression component activated by the electric component placed below the compression component; and a sealed container accommodating the electric component and the compression component; wherein the compression component includes: a shaft including a main shaft, and an eccentric shaft which is eccentric with respect to the main shaft; a cylinder block including a bearing having inside thereof a through-hole extending vertically and supporting the main shaft inserted into the through-hole such that the main shaft is rotatable, and a cylinder having a compression chamber inside thereof, a piston which is coupled to the eccentric shaft and is reciprocatable within the compression chamber; and a crank weight mounted to an upper portion of the eccentric shaft; wherein the rotor has a cylindrical shape and contains a cylindrical space therein; and wherein the rotor includes: an upper section in which a lower portion of the bearing is fitted into the cylindrical space; a lower section which is smaller in inner diameter than the upper section, a lower portion of the main shaft inserted into the through-hole of the bearing and inserted into the cylindrical space being fixedly fitted to the lower section; and a balance weight placed on an opposite side of the crank weight with respect to the piston.

In accordance with this configuration, since the lower portion of the bearing is fitted into the cylindrical space in the upper end portion of the rotor, the sealed compressor can be thinned while lessening the height which is a sum of the height of the rotor and the height of the bearing without a need to reduce the length of the bearing. This reduces a range in which the lower section of the rotor and the lower portion of the main shaft are fixedly fitted to each other is small, and the stiffness of the fitted portions is reduced. To avoid this, the forces and moments applied by the eccentric shaft and the piston to the shaft can be cancelled by the balance weight in addition to the crank weight. This makes it possible to prevent the vibration of the runout of the shaft in an inclined state. Therefore, it becomes possible to prevent a situation in which the vibration of the shaft is transmitted from the fitted portions with a low stiffness to the rotor and thereby the vibration of the rotor is amplified. As a result, the vibration and the noise in the sealed compressor can be reduced.

According to a second aspect of the present invention, in the sealed compressor according to the first aspect, a height of the upper section may be equal to or greater than 70% of a height of the rotor. In accordance with this configuration, the rotor and the bearing fitted thereinto overlap with each other in a great area, and as a result, the sealed compressor can be further thinned

According to a third aspect of the present invention, in the sealed compressor according to the first or second aspect, the compression component may further include a thrust ball bearing placed on a thrust surface of the bearing. In accordance with this configuration, a friction or the like between the thrust surface of the bearing and the eccentric shaft of the shaft can be mitigated by the thrust ball bearing, and hence the vibration and the noise which would be caused by them can be reduced.

According to a fourth aspect of the present invention, in the sealed compressor according to any one of the first to third aspects, a mass of the balance weight may be equal to or less than ⅕ of a mass of the crank weight. In accordance with this configuration, since the mass of the balance weight is reduced, the centrifugal force of the balance weight is reduced. This makes it possible to prevent the deformation of the rotor due to the centrifugal force of the balance weight and reduce the vibration and the noise, which would be caused by the deformation.

According to a fifth aspect of the present invention, in the sealed compressor according to any one of the first to fourth aspects, the balance weight may be placed on a lower surface of the rotor. In accordance with this configuration, since the balance weight placed on the lower surface is distant from the piston and the crank weight, unbalanced moment component can be cancelled by the balance weight with a small mass. Therefore, generation of the noise and the vibration due to the unbalanced moment component can be prevented. In addition, the lower section fixedly fitted to the main shaft and the balance weight are provided in the lower portion of the rotor such that they are close to each other. This makes it possible to prevent the deformation of the rotor, and hence generation of the vibration and the noise which would be caused by the deformation.

According to a sixth aspect of the present invention, in the sealed compressor according to any one of the first to fourth aspects, the balance weight may be placed on an upper surface of the rotor. In accordance with this configuration, the balance weight placed on the upper surface is distant from the liquid level of the lubricating oil reserved in the bottom portion of the sealed container. This makes it possible to prevent a situation in which the balance weight is immersed in the lubricating oil and stirs the lubricating oil, and formation of bubbles of the working fluid dissolved into the lubricating oil is facilitated. As a result, it becomes possible to prevent generation of the noise due to the lubricating oil contained in the bubbles of the working fluid.

According to a seventh aspect of the present invention, in the sealed compressor according to any one of the first to sixth aspects, the balance weight may be mounted to the rotor by a caulking pin. In accordance with this configuration, the stack structure composed of a plurality of steel plates constituting the rotor can be fastened together by the caulking pin, and the balance weight can be mounted to the rotor. This provides a high productivity.

According to an eighth aspect of the present invention, there is provided a refrigerator comprising the sealed compressor as recited in any one of the first to seventh aspects. In accordance with this configuration, the thinned sealed compressor allows the internal space of the refrigerator to be expanded, and the heat-insulating wall of the refrigerator to be increased. Thus, the refrigerator can be used more easily and the heat-insulating capability can be improved. Moreover, by the sealed compressor with the vibration mitigated, the noise and the vibration in the refrigerator can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Throughout the drawings, the same or corresponding components are identified by the same reference symbols and will not be described in repetition.

Embodiment 1

FIG. 1 is a cross-sectional view showing a sealed compressor 100. For easier understanding of the description, a direction parallel to the axis of a main shaft 123 of a shaft 119 will be referred to as a longitudinal (vertical) direction, while a direction which is perpendicular to the longitudinal direction will be referred to as a lateral direction.

As shown in FIG. 1, the sealed compressor 100 includes a compressor body 105 and a sealed container 101 accommodating the compressor body 105. The sealed compressor 100 is a device configured such that the compressor body 105 causes a working fluid to be in high-temperature and high-pressure states and the working fluid is discharged from the sealed container 101. The compressor body 105 is elastically supported by, for example, a suspension spring 107. The compressor body 105 includes an electric component 111 and a compression component 117 activated by the electric component 111.

The sealed container 101 is filled with lubricating oil 103 and the working fluid. The lubricating oil 103 is used for lubricating the compression component 117 for actuation and reserved in the bottom portion of the sealed container 101. As the working fluid, for example, hydrocarbon-based R600a (isobutane) which is low in global warming potential, or the like is used. A suction pipe (not shown) for suctioning the working fluid and a discharge pipe 104 for discharging the working fluid are connected to the sealed container 101. The sealed container 101 is provided with a power supply terminal 109 connected to the electric component 111.

The electric component 111 includes a stator 113 and a rotor 115 which rotates with respect to the stator 113, and, for example, a salient pole concentration winding DC brushless motor is used as the electric component 111. The stator 113 is configured such that a plurality of constituents are arranged in a substantially cylindrical shape. The constituents are configured such that copper windings are wound around a plurality of teeth of a core constructed of thin steel plates stacked together, via the insulating materials. The windings are continuous in all of the constituents and both ends thereof are connected to the power supply terminal 109. The rotor 115 has a cylindrical shape and contains a cylindrical space therein. The rotor 115 is placed inward relative to the stator 113. As will be described later, the rotor 115 is divided into two stages in the longitudinal direction in terms of a difference in inner diameter. The inner diameter of a boring section 116 formed by boring a hole in the rotor 115, which is located in the upper stage, is set greater than the inner diameter of a mounting section 115 e in the lower stage. The lower surface of the rotor 115 is attached with a balance weight 170. The balance weight 170 is placed on an opposite side of a crank weight 126 with respect to a piston 133.

The compression component 117 is placed above the electric component 111 and includes a shaft 119 activated by the electric component 111. The shaft 119 includes a cylindrical main shaft 123. The lower portion of the main shaft 123 is inserted into a cylindrical space of the rotor 115 and shrink-fit to the mounting section 115 e of the rotor 115. The lower end portion of main shaft 123 protrudes downward from the rotor 115 fitted with the lower portion of the main shaft 123, and is immersed in the lubricating oil 103 in the bottom portion of the sealed container 101. The main shaft 123 is provided with an oil feeding mechanism 128. The oil feeding mechanism 128 includes, for example, a communicating hole 130 b formed inside the main shaft 123, a centrifugal pump 130 mounted in the communicating hole 130 b, and a spiral groove 127 formed in the outer peripheral surface of the main shaft 123. The centrifugal pump 130 suctions up the lubricating oil 103 from a lower end opening 130 a of the communicating hole 130 b to the upper end opening of the communicating hole 130 b according to the rotation of the main shaft 123. The communicating hole 130 b is mainly provided inside the lower end portion of the main shaft 123 which protrudes downward from the lower end of the bearing 131. The lower end opening 130 a of the communicating hole 130 b opens in the lower end surface of the main shaft 123, while the upper end opening of the communicating hole 130 b opens in the outer peripheral surface of the main shaft 123. The upper end opening of the communicating hole 130 b is connected to the lower end of the spiral groove 127. The spiral groove 127 extends upward in a spiral form on the outer peripheral surface of the main shaft 123, between the outer peripheral surface of the main shaft 123 and the inner peripheral surface of the bearing 131. The upper end of the spiral groove 127 is connected to a region in the vicinity of sliding portions of the compression component 117.

The shaft 119 further includes an eccentric shaft 125 provided above the main shaft 123. The eccentric shaft 125 has a cylindrical shape and extends in parallel with the main shaft 123 such that the axis of the eccentric shaft 125 does not conform to the axis of the main shaft 123. The crank weight 126 is mounted to the upper end of the eccentric shaft 125. The crank weight 126 has, for example, a substantially sector shape along a plane perpendicular to the axis of the eccentric shaft 125, and has a hole in a center portion thereof The upper end portion of the eccentric shaft 125 is pressed into this hole, and thus the crankshaft 126 is fixedly fitted to the upper end of the eccentric shaft 125.

The shaft 119 further includes a flange 121 between the main shaft 123 and the eccentric shaft 125. The lower surface of the flange 121 is connected to the upper end of the main shaft 123. The upper surface of the flange 121 is connected to the lower end of the eccentric shaft 125. The flange 121 joins the main shaft 123 and the eccentric shaft 125 to each other. The flange 121 has, for example, a substantially sector form around the eccentric shaft 125 on a plane perpendicular to the axis of the eccentric shaft 125. The main shaft 123 is connected to the center portion of the flange 121. A portion of the flange 121, which has an arc-shaped portion of a substantially sector form, protrudes in a direction opposite to the eccentric shaft 125 from the main shaft 123. A bearing 131 of a cylinder block 129 is placed below the flange 121.

The cylinder block 129 includes the bearing 131 extending in the longitudinal direction and a cylinder 137 extending in the lateral direction. The bearing 131 has a substantially cylindrical shape. The lower portion of the bearing 131 is inserted into the cylindrical space of the boring section 116 of the rotor 115. The lower end of the bearing 131 is fixedly fitted to the mounting section 115 e in contact state. In this way, the lower portion of the bearing 131 is accommodated within the boring section 116, and the boring section 116 and the bearing 131 overlap with each other. This can reduce the height of the boring section 116 and of the bearing 131 without reducing the length of the bearing 131. As a result, the height of the sealed container 101 can be lessened.

The bearing 131 has therein a cylindrical through-hole extending in the longitudinal direction. The main shaft 123 is rotatably inserted into the through-hole. The bearing 131 radially supports the main shaft 123 on its inner peripheral surface. This provides a configuration of a cantilever bearing in which the shaft 119 is supported only by the bearing 131. The lower end portion of the main shaft 123 which is inserted into the through-hole protrudes downward from the lower end of the bearing 131 and is fixedly fitted to the mounting section 115 e of the rotor 115.

The bearing 131 bears on a thrust surface 196 as will be described later, a longitudinal load applied to the flange 121 via a thrust ball bearing 180. The longitudinal load applied to the flange 121 corresponds to a load which is a sum of the load of the shaft 119, the load of the crank weight 126 and the rotor 115 mounted to the shaft 119, and the load of the balance weight 170 mounted to the rotor 115.

The cylinder 137 has therein a cylindrical space extending in the lateral direction. A valve plate 139 is attached to the end surface of the cylinder 137. The valve plate 139 closes one end of the lateral cylindrical space. Thereby, a compression chamber 141 is formed inside the cylinder 137. A cylinder head 153 is fastened to the end surface of the cylinder 137 so as to cover the valve plate 139, and a suction muffler 155 is mounted between the valve plate 139 and the cylinder head 153. The suction muffler 155 is molded using a resin such as PBT (polybutylene terephthalate), and its internal muffling space can reduce the noise generated by the working fluid flowing from the suction pipe.

One end portion of the piston 133 is reciprocatingly inserted into the compression chamber 141 inside the cylinder 137, while the other end portion of the piston 133 is connected to a coupling section 143. The eccentric shaft 125 is coupled to the piston 133 in such a manner that a piston pin 135 mounted to the piston 133 is fitted into the hole provided in one end portion of the coupling section 143 and the eccentric shaft 125 is fitted into a hole provided in the other end portion of the coupling section 143.

FIG. 2 is an enlarged view showing a region A of FIG. 1. As shown in FIG. 2, the bearing 131 of the cylinder block 129 has the annular thrust surface 196 on the upper surface thereof The thrust surface 196 extends in a direction perpendicular to the center axis of the bearing 131. The center of the thrust surface 196 conforms to the center axis of the bearing 131. The inner diameter of the thrust surface 196 is greater than the inner diameter of the bearing 131. An annular extending section 194 is provided between the inner circle of the thrust surface 196 and the inner peripheral surface of the bearing 131. The annular extending section 194 has a cylindrical shape extending in the longitudinal direction. The axis of the annular extending section 194 conforms to the center axis of the bearing 131. The inner peripheral surface of the annular extending section 194 is continuous with the inner peripheral surface of the body of the bearing 131 and faces the outer peripheral surface of the main shaft 123.

The thrust ball bearing 180 is placed on the outer side of the annular extending section 194 of the bearing 131, between the flange 121 of the shaft 119 and the thrust surface 196 of the bearing 131. The thrust ball bearing 180 has a plurality of balls 186. The balls 186 are rolling elements. The plurality of balls 186 are equal in size to each other. The balls 186 are held in a cage 188. Instead of the thrust ball bearing 180, other ball bearings such as a roller bearing may be used.

The cage 188 is an annular flat plate member and is made of a resin material such as polyamide. The cage 188 has an inner peripheral surface which is in contact with the outer peripheral surface of the annular extending section 194 and includes a plurality holes inside thereof The plurality of holes are arranged in a circumferential direction thereof The balls 166 are rollably stored in the holes, respectively. The height of the cage 188 is smaller than the diameter of the balls 186. The balls 186 protrude in opposite directions of the longitudinal direction, from the cage 188. The balls 186 are sandwiched between an upper race 182 and a lower race 190 in the longitudinal direction, and held therein.

The upper race 182 and the lower race 190 are annular flat plate members, and are made of a metal, preferably, a spring steel or the like which has been subjected to a thermal treatment. The upper and lower surfaces of each of the races 182, 190 are parallel to each other and are formed to be flat. The upper race 182 is placed above the balls 186 and the cage 188. The upper surface of the upper race 182 is in contact with the lower surface of the flange 121, while the lower surface of the upper race 182 is in contact with the balls 186. The lower race 190 is placed below the balls 186 and the cage 188. The upper surface of the lower race 190 is in contact with the balls 186, while the lower surface of the lower race 190 is in contact with the upper surface of a support member 192. The support member 192 is an annular member having an elasticity. The upper surface of the support member 192 is in contact with the lower surface of the lower race 190, while the lower surface of the support member 192 is in contact with the thrust surface 196 of the bearing 131.

FIG. 3A is a cross-sectional view of the rotor 115, which is taken along a plane perpendicular to the axis of the rotor 115. FIG. 3B is a cross-sectional view of the rotor 115 which is taken along broken lines B-B of FIG. 3A. As shown in FIGS. 3A and 3B, the rotor 115 includes an upper end plate 115 c, a lower end plate 115 d, and a substantially cylindrical core 115 a sandwiched between the upper end plate 115 c and the lower end plate 115 d. The core 115 a includes a plurality of thin annular electromagnetic steel plates which are stacked together. Each of the electromagnetic steel plates has a plurality of (three in the present embodiment) circular holes for caulking pins 172 and a plurality of (six in the present embodiment) arc-shaped holes for permanent magnets 115 b. The permanent magnets 115 b are arc-shaped column members, and their height is set substantially equal to the height of the core 115 a. The end plates 115 c, 115 d are thin annular plates and have circular holes for the caulking pins 172, respectively.

The caulking pins 172 are inserted into the circular holes of the lower end plate 115 d, respectively. The core 115 a is placed on the lower end plate 115 d so that the caulking pins 172 are inserted into the circular-holes, respectively. Then, the permanent magnets 115 b are inserted into the arc-shaped holes of the core 115 a, respectively. The upper end plate 115 c is placed on the core 115 a. The upper end plate 115 c, the lower end plate 115 d, and the core 115 a are fastened together by the caulking pins 172 such that the upper end plate 115 c, the lower end plate 115 d, and the core 115 a adhere to each other. Finally, the permanent magnets 115 b (to be precise, magnet elements before being magnetized) accommodated in the core 115 a are magnetized, thereby constructing the rotor 115.

As described above, the rotor 115 is divided in the longitudinal direction according to a difference in the inner diameter, into the boring section 116 in the upper stage and the mounting section 115 e in the lower stage. The boring section 116 and the mounting section 115 e are identical to each other except for the inner diameter between the steel plates constituting the boring section 116 and the steel plates constituting the mounting section 115 e. The steel plates constituting the boring section 116 and the steel plates constituting the mounting section 115 e are fastened together by using the caulking pins 172, and thus the boring section 116 and the mounting section 115 e are unitarily constructed.

As shown in FIG. 3B, the inner diameter R1 of the boring section 116 is set greater than the inner diameter R2 of the mounting section 115 e. As shown in FIG. 1, the inner diameter R1 of the boring section 116 is set slightly greater than the outer diameter of the lower portion of the bearing 131. This allows the lower portion of the bearing 131 to be inserted into the cylindrical space of the boring section 116. Since the boring section 116 and the bearing 131 overlap with each other when viewed from a side, the height of the boring section 116 and of the bearing 131 can be lessened without reducing the length of the bearing 131. As a result, the height of the sealed container 101 can be lessened.

The inner diameter R2 of the mounting section 115 e is set smaller than the outer diameter of the lower portion of the bearing 131 and substantially equal to the outer diameter of the lower portion of the main shaft 123 of the shaft 119. The lower portion of the main shaft 123 penetrating the bearing 131 and protruding downward is inserted into the cylindrical space of the mounting section 115 e and fixedly fitted to the inner peripheral surface defining the cylindrical space.

As shown in FIG. 3B, the ratio of the height M of the boring section 116 with respect to the height L of the core 115 a of the rotor 115 is equal to or greater than 70%, while the ratio of the height N of the mounting section 115 e with respect to the height L of the core 115 a of the rotor 115 is equal to or less than 30%. For example, the boring section 116 with the height M of 30 mm and the mounting section 115 e with the height N of 6 mm are provided to correspond to the core 115 a with the height L of 36 mm In this case, the ratio of the height M of the boring section 116 with respect to the height L of the core 115 a is 83%. As should be understood, the ratio of the longitudinal dimension the boring section 116 with respect to the longitudinal dimension of the core 115 a is very large. This allows the sealed container 101 to be thinned On the other hand, the ratio of the longitudinal dimension of the mounting section 115 e with respect to the longitudinal dimension of the core 115 a is very small, and the mounting section 115 e and the main shaft 123 are fixedly fitted to each other in a small range. In addition, the core 115 a has a stacked structure in which the plurality of steel plates are stacked together in the longitudinal direction. Therefore, the lateral stiffness of the core 115 a to which the main shaft 123 is fixedly fitted is relatively low. An undesirable effect on the fitted portions by the inclination of the main shaft 123 is mitigated by the balance weight 170.

FIG. 4 is a view showing an external appearance of the rotor 115, when viewed from a lower side. As shown in FIGS. 3B and 4, the balance weight 170 is formed of a thin metal flat plate and is placed on the lower end plate 115 d of the rotor 115. The mass of the balance weight 170 is, as will be described later, determined by the forces and moments applied to the shaft 119. The mass of the balance weight 170 is smaller than the mass of the crank weight 126, and is set to, for example, ⅛ of the mass of the crank weight 126.

The balance weight 170 has a substantially arc-shape on a plane parallel to the lower surface of the rotor 115. The inner curve of the arc-shape of the balance weight 170 conforms to the inner periphery of the lower end plate 115 d, while the outer curve of the arc-shape of the balance weight 170 conforms to the outer periphery of the lower end plate 115 d and the outer periphery of the core 115 a. The balance weight 170 is provided to be symmetric with respect to a line parallel to the trajectory of the reciprocation motion of the piston 133 (FIG. 1), as indicated by one-dotted line C of FIG. 4. The balance weight 170 has two circular holes into which the caulking pins 172 are inserted, respectively. The two circular holes are placed to be symmetric with respect to one-dotted line C. The caulking pins 172 inserted into the circular holes allow the rotor 115 to be assembled and the balance weight 170 to be fastened to the lower surface of the rotor 115.

As described above, since the location at which the balance weight 170 is mounted to the rotor 115 and the location at which the rotor 115 and the shaft 119 are fixedly fitted to each other are close, the deformation such as a deflection of the rotor 115 can be prevented.

Next, the operation of the sealed compressor 100 as described above will be described. As shown in FIG. 1, a power supply (not shown) such as the power supply utility provided outside the sealed container 101 is connected to the power supply terminal 109 of the sealed container 101. Thus, AC power is supplied from the outside power supply to the electric component 111. In the electric component 111, the rotor 115 rotates by a magnetic field generated in the stator 113. Concurrently, the main shaft 123 of the shaft 119 fixedly fitted to the rotor 115 rotates and the eccentric shaft 125 coupled to the main shaft 123 via the flange 121 rotates eccentrically.

The coupling section 143 converts the eccentric rotation motion of the eccentric shaft 125 into a linear reciprocation motion. The piston 133 reciprocates inside the compression chamber 141 of the cylinder 137. According to the motion of the piston 133, the volume of the compression chamber 141 closed by the piston 133 changes. When the piston 133 moves in the direction for increasing the volume of the interior of the compression chamber 141, the working fluid flows from the suction pipe into the sealed container 101 and is suctioned into the compression chamber 141 via the suction muffler 155. On the other hand, when the piston 133 moves in the direction for reducing the volume of the interior of the compression chamber 141, the working fluid is compressed in the compression chamber 141 and then the working fluid in high-temperature and high-pressure states is sent from the sealed container 101 to a refrigeration cycle (not shown) via the discharge pipe 104 or the like.

According to the rotation of the main shaft 123, the lubricating oil 103 is suctioned up by the centrifugal pump 130 through the communicating hole 130 b. The lubricating oil 103 flows through the centrifugal pump 130 and moves upward along and on the inner wall of the communicating hole 130 b. The lubricating oil 103 reaches the upper end of the communicating hole 130 and then flows to the lower end of the spiral groove 127 on the surface of the main shaft 123. When the main shaft 123 rotates within the bearing 131, the lubricating oil 103 in the spiral groove 127 moves upward because of its viscosity between the outer peripheral surface of the main shaft 123 and the inner peripheral surface of the bearing 131, and lubricates sliding sections between them. Furthermore, the lubricating oil 103 is fed to the sliding sections of the compression component 117 through the eccentric shaft 125, the coupling section 143, or the like, to lubricate the sliding sections.

Since the lower portion of the bearing 131 is inserted into the boring section 116 of the rotor 115, the lower end portion of the main shaft 123 protruding downward from the lower end of the bearing 131 is short in length. The communicating hole 130 b provided inside the lower end portion of the main shaft 123 is also short in length, and the lifting range of the centrifugal pump 130 to feed the lubricating oil 103 through the communicating hole 130 b is reduced. Because of this, even when the rotational frequency of the main shaft 123 is low or the liquid level of the lubricating oil 103 is lowered temporarily, the centrifugal pump 130 can raise the lubricating oil 103 to the spiral groove 127 via the communicating hole 130 b. This makes it possible to sufficiently feed the lubricating oil 103 to the sliding sections. As a result, a reliability of the sealed compressor 100 can be improved.

When the flange section 121 rotates, the balls 186 of the thrust ball bearing 180 roll while point-contacting the upper race 182 and the lower race 190. This makes it possible to reduce a friction between the thrust surface 196 of the bearing 131 and the lower surface of the flange 121 of the shaft 119. Because of this, a driving power loss due to the friction can be reduced, and the mechanical efficiency of the sealed compressor 100 can be improved.

On the other hand, in the thrust ball bearing 180, the balls 186 are in point-contact with the races 182, 190. This causes a surface pressure to increase in a localized region. Therefore, it is necessary to feed the lubricating oil 103 to the thrust ball bearing 180. Regarding this, due to a reduction of the length of the communicating hole 130 b as described above, the lubricating oil 103 is sufficiently fed to the thrust ball bearing 180. Therefore, the thrust ball bearing 180 can be lubricated smoothly, and hence the durability of the thrust ball bearing 180 can be improved.

Next, the forces and moments applied to the shaft 119, in association with the balance weight 170, during the operation of the sealed compressor 100 will be described. FIG. 5 is a view schematically showing the forces applied to the shaft 119. As shown in FIG. 5, when the piston 133 reciprocates, an inertia force is generated in the piston 133. When the eccentric shaft 125 eccentrically rotates, a centrifugal force is generated in the eccentric shaft 125. Since the reciprocation motion of the piston 133 and the eccentric rotation motion of the eccentric shaft 125 are associated with each other, the inertia force of the piston 133 and the centrifugal force of the eccentric shaft 125 are applied to the shaft 119 in the same direction. For example, when the piston 133 moves in the direction for increasing the internal volume of the compression chamber 141 (FIG. 1), the inertia force of the piston 133 and the centrifugal force of the eccentric shaft 125 are applied to the shaft 119 in a direction of an arrow FA of FIG. 5. On the other hand, when the piston 133 moves in the direction for reducing the internal volume of the compression chamber 141 (FIG. 1), the inertia force of the piston 133 and the centrifugal force of the eccentric shaft 125 are applied to the shaft 119 in a direction which is opposite to the arrow FA of FIG. 5. This causes an unbalanced component FA which is a sum of the inertia force of the piston 133 and the centrifugal force of the eccentric shaft 125 to be applied to the shaft 119 in the direction in which the piston 133 reciprocates.

The crank weight 126 is mounted to the upper end of the eccentric shaft 125, and is positioned in a direction opposite to the eccentric shaft 125 with respect to the main shaft 123. The crank weight 126 rotates around the same rotational axis as that of the eccentric shaft 125 in association with the rotation of the eccentric shaft 125. For this reason, in the direction in which the piston 133 reciprocates, the centrifugal force FB of the crank weight 126 is applied to the shaft 119 in a direction opposite to the unbalanced component FA.

The balance weight 170 is mounted to the lower surface of the rotor 115 and is positioned in a direction opposite to the eccentric shaft 125 with respect to the main shaft 123. The balance weight 170 rotates around the same rotational axis as that of the main shaft 123 in association with the rotation of the main shaft 123. For this reason, in the direction in which the piston 133 reciprocates, the centrifugal force FC of the balance weight 170 is applied to the shaft 119 via the rotor 115 in a direction opposite to the direction of the unbalanced component FA and the same direction as that of the centrifugal force FB of the crank weight 126.

The mass of the crank weight 126 and the mass of the balance weight 170 are set so that a difference between the unbalanced component FA and the sum of the centrifugal force FB of the crank weight 126 and the centrifugal force FC of the balance weight 170 is smaller, and preferably zero. To this end, the loads FA, FB, FC are well balanced.

When the vertical distance (height) from the balance weight 170 to the center of the piston 133 is LAC, and the height from the center of the piston 133 to the crank weight 126 is LAB, a rotational moment M at the center of the piston 133 is expressed as M=FB×LAB−FC×LAC. The centrifugal force FB of the crank weight 126 and the centrifugal force FC of the balance weight 170 are set so that the moment FB×LAB and the moment FC×LAC cancel each other, and the rotational moment M is smaller and preferably zero. This allows the moments to be balanced as well as the forces applied to the shaft 119. This can suppress the vibration of the runout of the shaft 119 in an inclined state. Therefore, it becomes possible to prevent a situation in which the vibration of the rotor 115 is amplified by the vibration of the shaft 119, and to further reduce the noise and the vibration in the sealed compressor 100.

In a state in which the moment components are well balanced as described above, since the balance weight 170 is more distant from the piston 133 than the crank weight 126, the centrifugal force FC of the balance weight 170 is smaller than the centrifugal force FB of the crank weight 126. For example, in a case where a point of support is present in the center height of the piston 133, the mass of the balance weight 170 is ⅛ of the mass of the crank weight 126, if the height LAC is eight times as large as the height LAB. This significantly reduces the mass of the balance weight 170 mounted to the rotor 115, and also reduces the centrifugal force FC of the balance weight 170 which is applied to the rotor 115 even during a high-speed rotation. Therefore, even when the ratio of the height of the mounting section 115 e with respect to the height of the rotor 115 is small, the rotor 115 and the main shaft 123 are fixedly fitted to each other in a smaller range, and the stiffness of the fitted portion is relatively low, the force applied to the fitted portions is small. The lateral deflection of the core 115 a which is the stack of the steel plates, due to this force, can be prevented. As a result, it becomes possible to prevent a situation in which the shaft 119 vibrates by the runout due to the deformed rotor 115, and the noise is generated due to a change in a gap between the stator 113 and the rotor 115.

Especially, the balance weight 170 is mounted to the lower surface of the rotor 115 and is positioned to be most distant from the piston 133 among the constituents of the rotor 115. This reduces the mass of the balance weight 170 mounted to the lower surface as compared to a case where the balance weight 170 is mounted to another location, such as the upper surface of the rotor 115. Therefore, a bending moment applied to the mounting section 115 e of the rotor 115 can be reduced, and a deflection of the rotor 115 can be prevented. As a result, the vibration and the noise which would be caused by the deformation of the rotor 115 can be further reduced.

As shown in FIG. 1, the height of the boring section 116 of the rotor 115 is set greater and the height which is a sum of the height of the rotor 115 and the height of the bearing 131 is set smaller. This reduces a distance between the piston 133 located above the bearing 131 and a portion 101 a in which the suspension spring 107 supporting the compressor body 105 such as the piston 133 is fitted to the sealed container 101.

The vibration of the piston 133 which is a vibration source is more likely to be transmitted to outside the sealed compressor 100 via the suspension spring 107 and the fitted portions 101 a of the sealed container 101. In contrast, in the sealed compressor 100 of the present embodiment, by using the balance weight 170 in addition to the crank weight 126, the noise and the vibration in the sealed compressor 100 can be mitigated. As a result, the noise and the vibration which would be transmitted to outside the sealed compressor 100 can be lessened.

Moreover, since the vibration of the runout of the shaft 119, and the vibration generated in the sealed compressor 100 can be mitigated, it becomes possible to prevent a situation in which a biased load is applied to the balls 186 of the thrust ball bearing 180. As a result, a durability of the thrust ball bearing 180 can be improved.

Embodiment 2

The configuration of a sealed compressor 100 according to Embodiment 2 is substantially the same as that of the sealed compressor 100 according to Embodiment 1 except that the location of a balance weight 270 of Embodiment 2 is different from the location of the balance weight 170 of Embodiment 1. FIG. 6 is a cross-sectional view showing the sealed compressor 100 according to Embodiment 2.

As shown in FIG. 6, the balance weight 270 is mounted to the upper surface of the rotor 115 and placed on an opposite side of the crank weight 126 with respect to the piston 133. The mass of the balance weight 270 is, as will be described later, determined by the forces and moments applied to the shaft 119. The mass of the balance weight 270 is smaller than the mass of the crank weight 126, and is set to, for example, ⅕ of the mass of the crank weight 126.

Next, the forces and moments applied to the shaft 119, in association with the balance weight 270, during the operation of the sealed compressor 100, will be described. FIG. 7 is a view schematically showing the forces applied to the shaft 119. As shown in FIG. 7 in the direction in which the piston 133 reciprocates, the shaft 119 is applied with the unbalanced component FA which is a sum of the inertia force generated in the piston 133 by the reciprocation motion of the piston 133 and the centrifugal force generated in the eccentric shaft 125 by the eccentric rotation motion of the eccentric shaft 125. The centrifugal force FB of the crank weight 126 is applied to the shaft 119 in the direction opposite to the direction of the unbalanced component FA.

Further, the balance weight 270 is mounted to the upper surface of the rotor 115, and is positioned at an opposite side of the eccentric shaft 125 with respect to the main shaft 123. The balance weight 270 rotates around the same rotational axis as that of the main shaft 123 in association with the rotation of the main shaft 123. For this reason, in the direction in which the piston 133 reciprocates, the centrifugal force FD of the balance weight 270 is applied to the shaft 119 via the rotor 115 in a direction opposite to the direction of the unbalanced component FA and in the same direction as the direction of the centrifugal force FB of the crank weight 126.

The mass of the crank weight 126 and the mass of the balance weight 170 are set so that there is a balance between the unbalanced component FA and the sum of the centrifugal force FB of the crank weight 126 and the centrifugal force FC of the balance weight 170. When the vertical distance (height) from the balance weight 270 to the center of the piston 133 is LAD, the rotational moment M at the center of the piston 133 is expressed as M=FB×LAB−FD×LAD. The centrifugal force FB of the crank weight 126 and the centrifugal force FD of the balance weight 270 are set so that the moment FB×LAB and the moment FD×LAD cancel each other, and the rotational moment M is zero. Thereby, the forces applied to the shaft 119 are balanced, and the moments applied to the shaft 119 are balanced. This can prevent the vibration of the runout of shaft 119. Therefore, it becomes possible to further reduce the noise and the vibration in the sealed compressor 100.

In a state in which the moments are well balanced as described above, since the balance weight 270 is more distant from the piston 133 than the crank weight 126, the centrifugal force FD of the balance weight 270 becomes smaller than the centrifugal force FB of the crank weight 126. This can prevent the deformation of the rotor 115 and the vibration of the runout of the shaft 119, and hence prevent the vibration and the noise in the sealed compressor 100. In addition, as shown in FIG. 7, it becomes possible to reduce the vibration and the noise transmitted from the sealed container 101 to outside the sealed compressor 100 via the suspension spring 107.

Moreover, the balance weight 270 is placed above the rotor 115 and is distant from the liquid level of the lubricating oil 103 reserved in the bottom portion of the sealed container 101 as shown in FIG. 6. In this structure, when the rotor 115 rotates, it becomes possible to prevent a situation in which the balance weight 270 is immersed in the lubricating oil 103 and stirs the lubricating oil 103. Even if the working fluid is dissolved into the lubricating oil 103, it becomes possible to prevent a situation in which the working fluid generates bubbles in the lubricating oil 103 due to the stirring by the balance weight 270. As a result, it becomes possible to prevent a situation in which the bubbles of the working fluid, containing the lubricating oil 103, are suctioned into the compression chamber 141, are compressed by the piston 133 in the interior of the compression chamber 141, and generate the noise.

Embodiment 3

FIG. 8 is a cross-sectional view schematically showing a refrigerator 200 according to Embodiment 3. As shown in FIG. 8, the refrigerator 200 includes a heat-insulating casing 202 having a heat-insulating space inside thereof and doors attached to the heat-insulating casing 202 to open and close the heat-insulating space. The surface of the heat-insulating casing 202 attached with the doors is a front surface and the opposite surface is a back surface.

The heat-insulating casing 202 has a substantially rectangular parallelepiped shape which is elongated in the longitudinal direction. The heat-insulating casing 202 includes a heating insulating wall defining the heat-insulating space inside thereof, and partition plates for partitioning the heat-insulating space into a plurality of (five in the present embodiment) heat-insulating space sections 210, 212, 214, 216, 218. The five heat-insulating space sections 210, 212, 214, 216, 218 are vertically separated as four stages. The heat-insulating space section in the second stage from the upper is separated into two parts in a rightward or leftward direction. For example, the heat-insulating space section in the first stage from the upper is used as a chill room 210, the two heat-insulating space sections in the second stage from the upper are used as a switch room 212 and an ice making room 214, the heat-insulating space section in the third stage from the upper is used as a vegetable room 216, and the heat-insulating space section in the fourth stage from the upper is used as a freezing room (compartment) 218. The heat-insulating space sections 210, 212, 214, 216, 218 are connected to each other via ducts (not shown), and dampers are provided inside the ducts. The ducts allow air communication among the respective heat-insulating space sections. The flow rate of the air is adjusted by the dampers. The heat-insulating space sections 210, 212, 214, 216, 218 are partially or entirely provided with temperature sensors (not shown).

The heat-insulating casing 202 includes an inner casing 204 and an outer casing 206 provided outside the inner casing 204. The inner casing 204 is manufactured by vacuum-molding using a resin such as ABS. The inner casing 204 constitutes the inner surface of the heat-insulating wall defining the heat-insulating space and the partition plates for partitioning the heat-insulating space. The outer casing 206 is made of metal such as a pre-coat steel plate, and constitutes the outer surface of the heat-insulating wall. A heat-insulating material 208 is unitarily foamed and filled in a space formed between the inner casing 204 and the outer casing 206, thus constructing the heat-insulating casing 202. In this way, the heat-insulating wall and the partition plates are formed together and unitarily. As the heat-insulating material 208, for example, foamed plastic such as a hard urethane foam, a phenol foam, or a styrene foam is used. As this foamed material, for example, a hydrocarbon-based cyclopentane is used to prevent global warning.

The heat-insulating casing 202 is provided with a recess 230 formed by denting a part of its back surface and its upper surface. The sealed compressor 100 is elastically supported in the recess 230. A condenser (not shown) and a drier (not shown) for removing a moisture are placed on the side surface or the like of the heat-insulating casing 202. In addition, a capillary 234 which is a pressure-reducing unit and an evaporator 238 are placed on the back surface of the heat-insulating casing 202. A cooling fan 236 and the evaporator 238 are placed on the back surface of the vegetable room 216 and the back surface of the freezing room 218 in the interior of the heat-insulating casing 202. The sealed compressor 100, the condenser, the capillary 234 and the evaporator 238 are connected together in an annular shape by a pipe 240, thus constituting a refrigeration cycle. Furthermore, the heat-insulating casing 202 is provided with a controller (not shown). The temperature sensors placed in the heat-insulating space sections are connected to the controller. In addition, the sealed compressor 100, the condenser, the drier, the capillary 234, the evaporator 238, the cooling fan 236 and the evaporator 238 are connected to the controller. The controller controls these components based on the detection values of the temperature sensors.

In the present embodiment, five doors 220, 222, 224, 226, 228 are attached to the heat-insulating casing 202 such that the doors 220, 222, 224, 226, 228 can open and close the front surfaces of the heat-insulating space sections 210, 212, 214, 216, 218 in the interior of the heat-insulating casing 202. The chill room 210 is provided with a rotatable door 220, while the switch room 212, the ice making room 214, the vegetable room 216, and the freezing room 218 are provided with drawing doors 222, 224, 226, 228, respectively. The rotatable door 220 and the drawing doors 222, 224, 226, 228 are each constructed by bonding a decorative sheet to the heat-insulating material such as foamed polystyrene. Between the doors 220, 222, 224, 226, 228 and the heat-insulating casing 202, gaskets are placed, which can keep the heat-insulating space sections 210, 212, 214, 216, 218 in a sealed state.

Next, the operation of the refrigeration cycle of the above described refrigerator 200 will be described. The controller starts and stops the cooling operation based on the detection signals from the temperature sensors. Upon the start of the cooling operation, the working fluid is compressed by the reciprocation motion of the piston 133 (FIG. 1) in the sealed compressor 100, and the working fluid in the high-temperature and high-pressure states is sent from the discharge pipe 104 (FIG. 1) to the refrigeration cycle through the pipe 240. The gaseous working fluid in the high-temperature and high-pressure states radiates heat in the condenser, and is condensed into a liquid. The liquid working fluid is pressure-reduced in the capillary 234 to be turned into low-temperature and low-pressure states, and reaches the evaporator 238. The cooling fan 236 operates to cause the air in the vegetable room 216 and the freezing room 218 to migrate, and this air exchanges heat with the working fluid in the low-temperature state in the evaporator 238. The working fluid raises its temperature and is evaporated. The evaporated working fluid is returned to the sealed compressor 100 through the pipe 240. In contrast, the cooled air is delivered to the heat-insulating space sections 210, 212, 214 via the ducts. At this time, the flow rates of the cooled air delivered to the heat-insulating space sections 210, 212, 214 are adjusted via the dampers, so that the heat-insulating space sections 210, 212, 214, 216, 218 are adjusted at proper temperatures, respectively.

For example, the temperature of the chill room 210 is a temperature at which stuff are not frozen and preserved in a chilled state, for example, 1 to 5 degrees C. The switch room 212 is set to a temperature which can be changed by the user, and is placed at the set temperature. This set temperature may be set to, for example, a specified temperature in a range from a temperature zone of the freezing room 218 to a temperature zone of the vegetable room 216. The ice making room 214 includes an automatic ice making device (not shown), and is configured to automatically make ice and reserve the ice. To preserve the ice, the ice making room 214 is adjusted at a temperature which is relatively higher than the freezing temperature zone, for example, minus 18 to minus 10 degrees C. The vegetable room 216 is adjusted at a temperature which is equal to or slightly higher than that of the chill room 210, for example, 2 to 7 degrees C. As this temperature is lower and is not a freezing temperature, the freshness of the vegetables can be kept for a long time. The freezing room 218 is normally adjusted at minus 22 to minus 18 degrees C. to preserve stuff in a frozen state. However, to preserve the stuff in a more frozen state, for example, the freezing room 218 may be adjusted at minus 30 to minus 25 degrees C.

The refrigerator 200 incorporates the sealed compressor 100 provided with the crank weight 126 and the balance weight 170, 270 of FIGS. 1 and 6. In this case, the forces and rotational moments which cannot be cancelled merely by the crank weight 126 are cancelled by the balance weight 170, 270. Since the vibration of the sealed compressor 100 can be mitigated during the operation, the vibration and noise in the refrigerator 200 can be reduced.

Since the rotor 115 and the bearing 131 overlap with each other because of the boring section 116 of FIGS. 1 and 6, the height of the sealed compressor 100 can be lessened. Because of this, the depth of the recess 230 on the heat-insulating casing 202 is allowed to be small, which can increase the size of the heat-insulating space in the interior of the refrigerator 200, and the thickness of the heat-insulating material 208. Therefore, the refrigerator 200 can be used more easily and its heat-insulating capability can be improved.

Since the partition plates and the heat insulating wall in the heat-insulating casing 202 are constructed by unitarily filling the foamed material, a cost reduction and improvement of a heat insulating capability can be achieved. Since the partition plates manufactured in this way have a heat-insulating capability which is about twice as high as that of the heat-insulating member of the foamed polystyrene, the partition plates can be thinned, and correspondingly the heat-insulating space can be expanded.

Other Embodiments

Although in Embodiment 3, the sealed compressor 100 is incorporated into the refrigerator 200, it may be used in devices using refrigeration cycles (heat pump cycles) such as air conditioners, automatic dispensers, other freezing devices, and further, industrial compressors such as air compressors.

Although in Embodiment 3, the partition plates and the heat-insulating wall are formed unitarily in the heat-insulating casing 202, they may be formed separately.

The above embodiments may be combined so long as they do not exclude each other.

Numeral modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, the description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and/or function may be varied substantially without departing from the spirit of the invention.

INDUSTRIAL APPLICABILITY

As described above, a sealed compressor and a refrigerator including the sealed compressor of the present invention are useful as a thinned sealed compressor which is capable of reducing a vibration and a noise, and a refrigerator including the thinned sealed compressor.

REFERENCE SIGNS LIST

100 sealed compressor

101 sealed container

111 electric component

113 stator

115 rotor

115 e mounting section (lower section)

116 boring section (upper section)

117 compression component

119 shaft

123 main shaft

125 eccentric shaft

126 crank weight

129 cylinder block

131 bearing

133 piston

137 cylinder

141 compression chamber

170 balance weight

172 caulking pin

180 thrust ball bearing

200 refrigerator

270 balance weight 

1. A sealed compressor comprising: an electric component including a stator and a rotor which is rotatable with respect to the stator; a compression component activated by the electric component placed below the compression component; and a sealed container accommodating the electric component and the compression component; wherein the compression component includes: a shaft including a main shaft, and an eccentric shaft which is eccentric with respect to the main shaft; a cylinder block including a bearing having inside thereof a through-hole extending vertically and supporting the main shaft inserted into the through-hole such that the main shaft is rotatable, and a cylinder having a compression chamber inside thereof; a piston which is coupled to the eccentric shaft and is reciprocatable within the compression chamber; and a crank weight mounted to an upper portion of the eccentric shaft; wherein the rotor has a cylindrical shape and contains a cylindrical space therein; and wherein the rotor includes: an upper section in which a lower portion of the bearing is fitted into the cylindrical space; a lower section which is smaller in inner diameter than the upper section, a lower portion of the main shaft inserted into the through-hole of the bearing and inserted into the cylindrical space being fixedly fitted to the lower section; and a balance weight placed on an opposite side of the crank weight with respect to the piston.
 2. The sealed compressor according to claim 1, wherein a height of the upper section is equal to or greater than 70% of a height of the rotor.
 3. The sealed compressor according to claim 1, wherein the compression component further includes a thrust ball bearing placed on a thrust surface of the bearing.
 4. The sealed compressor according to claim 1, wherein a mass of the balance weight is equal to or less than ⅕ of a mass of the crank weight.
 5. The sealed compressor according to claim 1, wherein the balance weight is placed on a lower surface of the rotor.
 6. The sealed compressor according to claim 1, wherein the balance weight is placed on an upper surface of the rotor.
 7. The sealed compressor according to claim 1, wherein the balance weight is mounted to the rotor by a caulking pin.
 8. A refrigerator comprising the sealed compressor as recited in claim
 1. 